The ledger transactions report (as well as the related monthly and yearly transactions reports) are reports which show transactions in columns across the page. The problem with this report is that eventually you run out of page space if you have a very large number of income or expense categories. So this report is designed to split the transactions totals and column headings into multiple rows if there are a large number of categories, so this reduces the chance of the columns joining together.
This report has now been changed so that when output to file, the row splitting no longer happens. This is because a file has no width limitation like a screen or printed page does. So you can output the report to a CSV file and open it in Excel and all the column heading and totals will line up correctly.